Wireless networks such as wireless local area networks (WLANs) are known. In a WLAN, stations (STAs) are able to communicate wirelessly within a local network. In an infrastructure network, all communication is via an access point (AP) that acts as a base station. Any entity on the WLAN can also communicate with a node on any other wired or wireless network that is connected to the WLAN, e.g., via the access point.
Mobile IP is a well known extension of the Internet Protocol (IP) that enables a node on an IP-based network to change its physical attachment point in the network, e.g., the Internet, while retaining the same IP address by which it is identified on its home network. Agents such as home agents and foreign agents (collectively, “mobility agents”) that provide Mobile IP services send IP packets that include advertisements of the services they provide. Thus, determining availability of Mobile IP services is a process that occurs at the network layer (L3) of the communication protocol.
The association of a wireless station to an access point occurs at the data link layer (L2), i.e., at a lower protocol layer than Mobile IP services. Thus, in the prior art, the association between an AP and a station occurs at a protocol layer wherein there is ignorance of Mobile IP services, and thus occurs without regard to whether the AP is in communication with any mobility agents.
Above-mentioned and incorporated-by-reference U.S. patent application Ser. No. 10/263,632 to Molteni, et al., titled AN L2 METHOD FOR A WIRELESS STATION TO LOCATE AND ASSOCIATE WITH A WIRELESS NETWORK IN COMMUNICATION WITH A MOBILE IP AGENT, (hereinafter the “Parent Invention”) describes how a wireless station can create a database of WLAN access points that the station can hear, called the WLAN database herein. The WLAN database includes for each WLAN whose AP the station can hear L2 information such as the Service Set Identifier (SSID) of the wireless network that uniquely identifies the WLAN, and the signal strength of L2 frames from the AP of the WLAN. The WLAN database also includes L3 information such as any advertisements from mobility agents that the AP of the WLAN transmits. Such L3 information is collected at L2 prior to the station being associated with any AP.
The Parent Invention provides a method and apparatus that enables a station of a WLAN to discover, prior to association, whether or not one or more candidate APs for association that are in communication with mobility agents, e.g. with home agents and/or foreign agents. The parent invention also describes selecting for association a WLAN from the WLAN database whose AP is in communication with a mobility agent so that the wireless station can benefit from and/or provide Mobile IP services. When the station is in communication with a foreign agent (IPv4) or access router (IPv6), the wireless station can become a mobile node. A mobile node is a node of a network that can change its point of attachment.
One aspect of the Parent Invention is when the station is a router. By ensuring that the router associates with a WLAN whose AP transmitted a foreign agent advertisement from a foreign agent (in the case of IPv4) or from an access router (in the case of IPv6), the router also becomes a mobile node by associating with a WLAN in communication with the foreign agent (or access router). A router that is a mobile node is called a mobile router.
While the WLAN database may provides information on the signal strength of the wireless link between the station and the APs of the WLANs in the WLAN database, there is no latency information provided regarding communication between the station and the AP of the WLAN. Furthermore, there is no information provided regarding the communication link beyond the AP of the WLAN. It would be advantageous for the station to also have available other network performance metrics such as response time useful, for example, as quality of service (QoS) parameters, and not only of the wireless link to the AP, but also of the link to the mobility agent (in the case of Mobile IP services) or of the link to any other service provider in the general case.
Such quality of service information is useful, for example, if the station is to participate in voice over IP (VoIP) or other services wherein such network performance metrics as one or more of the response time, availability, jitter (interpacket delay variance), connect time, throughput, and packet loss are important.